Sudden mounting from submissive rabbit .

So I have a trio Patch (female) Nesquik (Female) and Peter (Male) all have been neutered bonding went amazingly well Peter has diffused any tension between the girls (who are bonded but have had power struggles in the past) and dominance issues they have been resolved or so I thought I brought them out into the garden today in the run all seemed fine until Patch the normally submissive one out the sisters began mounting Peter then Nesquik then she pulled some of Nesquik fur out , Nesquik then mounted her back and so forth and so on. They have gone back into their room all together and seem happy back in their own terrority but has putting them in neutral terrority thrown them? I'm worried I've ruined their bond Nesquik is firmly top bunny in the house is it normal for rabbits to mount in every new place?

It seems with some rabbits that when placed in a new situation they have to re-sort their hierarchy, so I don't understand why the submissive one was mounting. I hope they have now calmed down again!